Characterization Of Geothermal Resources Using New Geophysical Technology

Conference Paper: Characterization Of Geothermal Resources Using New Geophysical Technology

Abstract

This paper presents a geothermal case history using a relatively new but proven technology that can accurately map groundwater at significant depths (up to 1,000 meters) over large areas (square kilometers) in short periods of time (weeks). Understanding the location and extent of groundwater resources is very important to the geothermal industry for obvious reasons. It is crucial to have a cost-effective method of understanding where concentrations of geothermal water are located as well as the preferential flow paths of the water in the subsurface. Such information can assist companies to optimize the location of production and injection wells among other things. AquaTrack is a patented, geophysical magnetic-based groundwater mapping solution, from Willowstick Technologies, LLC that has proven successful in the geothermal industry to better characterize groundwater conditions and flow patterns. AquaTrack's technical name is Controlled Source-Frequency Domain Magnetics (CS-FDM) and will be referred to as such hereafter in this paper. A description of how the technology works and a review of a case study will be presented. This paper will focus on how a geothermal company used the AquaTrack technology to gain insightful understanding of groundwater flow. Project History and Background Global environmental standards continue to become ever more stringent, increasing the appeal and demand for green power. Because of this, geothermal energy is experiencing enormous growth. As a part of this growth, Amp Resources (Amp) recently purchased the Salt Wells geothermal site near Fallon, Nevada. This geothermal resource has long been believed to be marginal because of its lower water temperatures in comparison to traditional geothermal resources. Amp Resources looked to new and emerging technologies to assist them in the exploration of their newly acquired asset. As a result, they turned to Willowstick Technologies, LLC (Willowstick). Willowstick was contracted to assist Amp to better characterize and delineate areas of greatest geothermal groundwater concentrations and highest groundwater temperatures. This geophysical investigation proved to play a key part in Amp Resources' placement of geothermal production wells, injection wells, and a geothermal power plant at Salt Wells. A significant amount of geothermal exploration work had been conducted at the Salt Wells site including: exploratory well drilling, hydrogeologic reconnaissance, temperature gradient holes, soil-mercury surveys, self-potential and gravity and magnetic surveys. However, none of the surveys clearly identified where high temperature groundwater was located and how best to develop the resource for optimal electrical power production. Amp Resources also retained the services of Roger L. Bowers, P.G. to review the CS-FDM results from Willowstick Technologies and compare its findings with the other geothermal exploration surveys previously done for the Salt Wells site. Upon Mr. Bowers review of the CS-FDM work, and after comparing its results with previous studies, Mr. Bowers assisted in the preparation of the final report submitted to Amp Resources